Method of sealing coaxial structures



April 20, 1948. L. c. WERNER ETAL METHOD OF SEALING COAXIAL STRUCTURES Filed March l,- 1945 NTORS 4. c. WEe/VEE 14 s. z. u v BY W MLuMw-wi INVE TTORNEY Patented Apr. 20, 1948 METHODOESEALING'COAXIAL V STRUCTURES Leo Werner andWillard S. Lund; Bloomfield, 1 N. J.) assignors-to=Westinghouse=Electric Corporation, East Pittsburgh, -Pa;, acorporation of 1 Pennsylvania .ApDlicationManch 1, 1945 Serial No. 580,386

(Cl. 49-t-81) This invention relates to a method of sealin coaxial structuresan-d more particularly to application of glass. insulatingv beads-at intervals within a length of tubing between the tubing wall and a coaxial-rod within the said tubing.

Heretofore insulating beads have been applied in tubing by applying the glassinvdes-ired position and then inserting plungers from opposite endsuof the tubing to press-the glass, whilein plastic condition, and therebysqueezeit-into adhering contact with the-tube-wall. Obviously such a method admitsof application or" onl one bead withina length of tube.

An object ofthe presentinvention is toenable 1a glurality of insulating beads-to be formed in a Another objectof the invention is to provide a coaxial structure with an integral length thereof having firmly secured successive insulating beads therein.

A further objectof the invention is toproyide animproved method for fabrication of coaxial lines with successive beads.

Still further objects of the invention will appear to those skilled in the art to which it appertains as the description progresses both by direct recitation thereof and by implication from the context.

Referring to the accompanying drawing in which like numerals of reference indicate similar parts throughout the several views:

Figures 1 is an elevation of a length of coaxial line broken away at a middle part to show interior structure and fabricated in accordance with our invention;

Figures 2 and 3 are sectional elevations showing the steps of forming the glass buttons on the rod section of the coaxial structure; and

Figures 4 and 5 show successive steps in completion of the seals after insertion of the rod section into the tubular section.

In the specific embodiment of the invention illustrated in said drawing, the reference numeral l0 designates the inner or rod member of a coaxial structure, and numeral ll denotes the outer or tubular member; The completed structure shows these sections coaxially secured by a plurality of successive glass beads l2 sealed to both members. Heretofore, since it was necessary to insert plungers ,at opposite sides of the glass head to force it into sealing contact with the tubular member, only one bead could be applied in a tube and the tubular member therefore had to be undesirably short in order that the inner conductor or member would be adequately supportedto assure its-coaxial position. According tothe present invention, th inner member or rod is supported by a plurality of meltable beads 12 in a lengthof outer member, and the length depends only'on' the capacity of the machine used in its manufacture to-receive it. For brevity, said beads will be considered as made of glass, but other materials may be employed having the characteristic of softening under influence of heat to a viscous flowing-condition.

' Following the successive steps of manufacture, the rod-0r inner member l0- is-first prepared with glass-or other buttons thereon,- which ultimately become the sealed beads 12. For illustrating completely-one exemplification of the method throughout its several. steps, Figure 2 indicates that first a cut length of glass tubing 12* is applied to the rod I0 at the position where a bead is desired. By flame l3 or other suitable means, thejglass tubing I2 is softened until it wets or adheres to the rod with the rod rotating as indicated. by arrow 2-00 in Fig. 2. Successive lengths of glass tubing l2 are similarly applied along the rod at all places where beads are desired. Each length of glass tubing I2 thus applied to the rod is then built up between its ends by addition of more glass from a stick l4 by use of flame l5 or other suitable means until a button l2 of desired bulk and diameter is formed. Preferably the addition of glass from stick I4 is accomplished while rod I0 is rotating, as indicated by arrow 2), so the forming operation will result in a circular and coaxial button l2 the diameter of which is limited to less than, but substantially equal to the inside diameter of the tubular member ll into which the rod, with its several buttons formed thereon, is next inserted. Both the rod or inner member l0 and the tube or outer member H are preferably secured by suitable means, of which chuck i6 is indicative, to the rotating head stock of the machine so that both will be positively rotated and at the same number of revolutions per minute. The tub or outer member H is pressed longitudinally toward the chuck by a rotatable tail stock spindle l8. An electrical coil I! for high frequency induction heating is applied around the tube, loose with respect thereto so as not to interfere with rotation of the tube while the coil remains fixed. With the apparatus thus arranged, the coaxial members are thereupon, as indicated by arrow 220 in Fig. 4, rotated simultaneously at a slow speed and heating is applied as by the electrical high frequency induction from coil ll. The glass of buttons l2 becomes hot from this heating,

and at the stage when the glass begins to soften and become soft, the apparatus is speeded up to high speed, say about 2,000 revolutions per minute. The rotation at this increased speed is indicated by arrow 230 in Fig. 5. By virtue of this increased speed, the softness of the glass and centrifugal action, the glass flows into forceful and wetting engagement with the interior surface of the tubular member and seals therewith as final beads 12 above mentioned. When the seal is efiected, the rotation and heat are discontinued.

It will be observed that the glass buttons 12*, by having substantially the inside diameter of the tube i 0, maintain the rod coaxial to the tube, and that this coaxial relationship is maintained as the glass softens during rotation and heating while effecting the seal. Thus the final assembly provides a coaxial structure with a plurality of successive beads maintaining the coaxial relationship of tube and rod. The heating, rotation and centrifugal action during the sealing operation are equally effective upon all the buttons, and therefore the several beads formed are all equally sealed and have corresponding configurations and afford equal spacing and support for the rod within the tube.

We claim:

1. A method of sealing coaxial structures having inner and outer members comprising applying a plurality of meltable buttons on the inner member of said structure, inserting the inner member into the outer member, rotating said members While heating the meltable buttons to a viscous flowing temperature, and engaging the buttons in flowing condition centrifugally against the outer member of the coaxial struc-' ture.

2. A method of sealing coaxial structures having inner and outer members, comprising applying a plurality of meltable buttons on the inner member of said structure, inserting the inner member into the outer member, rotating said members and simultaneously heating the meltable buttons to a viscous flowing temperature, engaging the buttons in flowing condition centrifugally against the inner wall of the outer memberof the coaxial structure, and continuing application of heat and centrifugal action on the buttons until they wet and seal to said inner wall and form beads sealed thereto.

8. A method of sealing coaxial structures having inner and outer members, comprising first sealing lengths of glass tubing to the inner member at successive intervals where beading is desired, building up the diameter of glass as a button on each length of tubing, inserting the inner member with the built-up buttons thereon into the outer member, rotating said members, and heating said buttons and centrifugally flowing the glass thereof into sealing engagement with the outer member.

LEO C. WERNER. WILLARD S. LUND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain Oct. 14, 1936 

